Does Microsoft.Extensions.Http.Resilience works for Blazor project?

[aDisplayName]

The way HttpClient is configured in Blazor WASM project is via the use of IServiceCollection.AddScoped<T>()

builder.Services
    .AddScoped(sp => new HttpClient 
        { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) })

The extension method of IHttpClientBuilder.AddStandardResilienceHandler is an extension on IHttpClientBuilder. So my question is can Microsoft.Extensions.Http.Resilience be used for Blazor WASM project?

I tried to disable the AddScoped in setup, and instead of using

builder.Services.AddHttpClient<MyService>(x => x.BaseAddress = new Uri(builder.HostEnvironment.BaseAddress))
    .AddStandardResilienceHandler();

and it seems it doesn't work at all, an exception is thrown:

System.InvalidOperationException An invalid request URI was provided. Either the request URI must be an absolute URI or BaseAddress must be set

Would be great if the resilience library be used for Blazor as well.

@martintmk @danroth27

[danroth27]

That error basically says the HttpClient is being asked to make a request to a relative URI without a specified base address. What's the stack trace for that exception? Can you confirm whether the used HttpClient has a valid base address or not?

[aDisplayName]

Hi, @danroth27 ,

So the original code in Program.cs in my Blazor WASM is

using Microsoft.AspNetCore.Components.Web;
using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
using Microsoft.FluentUI.AspNetCore.Components;
using Slb.Everest.Wbi.Sealy.Portal.Web.Client.Services;

var builder = WebAssemblyHostBuilder.CreateDefault(args);


builder.Services
    .AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) })
    .AddScoped<MyService>();

builder.Services.AddFluentUIComponents();
builder.Services.AddTelerikBlazor();
builder.RootComponents.Add<HeadOutlet>("head::after");

await builder.Build().RunAsync();

And it works without any problem.

In order to use the IHttpClientBuilder.AddStandardResilienceHandler, I've added Microsoft.Extensions.Http.Resilience nuget package, and changed the program.cs into

using Microsoft.AspNetCore.Components.Web;
using Microsoft.AspNetCore.Components.WebAssembly.Hosting;
using Microsoft.FluentUI.AspNetCore.Components;
using Slb.Everest.Wbi.Sealy.Portal.Web.Client.Services;

var builder = WebAssemblyHostBuilder.CreateDefault(args);

builder.Services.AddHttpClient<ProjectGatewayService>(x => x.BaseAddress = new Uri(builder.HostEnvironment.BaseAddress))
    .AddStandardResilienceHandler();

builder.Services
    // Replaced with .AddHttpClient<> above
    // .AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) })
    .AddScoped<MyService>();


builder.Services.AddFluentUIComponents();
builder.Services.AddTelerikBlazor();
builder.RootComponents.Add<HeadOutlet>("head::after");

await builder.Build().RunAsync();

And the exception thrown when calling the inject the httpclient when calling with a relative path. Apparently the BaseAddress was not being set.

I guess the actual question is, does Blazor app support using IHttpClientBuilder AddHttpClient<TClient>(this IServiceCollection services, Action<HttpClient> configureClient) extenstion method to inject HttpClient.